Aerator



March 9, 1937. A, c. DURDIN, 3D 2,072,944

AERATOR Filed Dec. 21, 1934 2 Sheets-Sheet l INVENTOR.

ATTORNEY.

March 9, 1937.

A. c. DURD IN, 3D 2,072,944

AERATOR Filed Dec. 21, 1934 2 Sheets-Sheet 2 1N VENTOR.

ATTORNEY.

Patented Mar. 9, 1937 UNITED STATES AERATOR Au ustus c. Durdin, m, Niles Center, 111.; mumto Chicago Pump Company, Chicago, III., a

corporation of Illinois Application December 21, 1934, Serial No. 758,631

12 Claims.

This invention relates to aerators and its principal object is to provide means for impregnating liquids with an abundant supply of air or other gas. In its present form, the aerator has been shown in connection with a sewage treatment plant, but it is to be understood that its use is not limited thereto, as it may be employed in any situation where liquids are to be impregnated with air or other gases.

Another object is to provide an aerator having means for propelling the liquid to be treated, in combination with mixing means, operating to supply abundant quantities of air to the liquid propelled against it by the propeller. Another object is to provide an aerator in which the liquid propelling means and the mixing means may be formed as a single unit or may be made separate from each other, and in which the propelling means and the mixing means may rotate toether or the mixing means may rotate independently of the propelling means or may be mounted against rotation.

Other objects and advantages will appear in the course of this specification and with said objects and advantages in view, this invention consists in the several novel features hereinafter fully set forth and claimed.

The invention is clearly illustrated in the drawings accompanying this specification, in which:

Fig. l is a vertical section through a sewage treatment tank equipped with an aerator embodying the preferred form of the invention;

Fig. 2 is a plan of the parts seen in Fig.1;

Fig. 3 is a detail side elevation of the preferred form of aerator, looking in the direction of the arrow 3 in Fig. 5;

Fig. 4 is a side elevation of the aerator, seen in Fig. 3, looking in the direction of thearrow 4 in Fig. 5;

Fig. 5 is a plan of the aerator;

Fig. 6 is a side elevation of a slightly modified form of aerator showing the same in connection with a certain conduit, the latter being shown in section;

Fig. '7 isja similar view of a second modified form and Fig. 8 is a similar view of a third modification.

Referring to said drawings, which illustrate the application of the aerator to a sewage treatment plant, and referring first to Figs. 1 to 5 inclusive, the reference character l0 designates an aerating tank, usually provided with a hopper like bottom II. A sewage inlet pipe l2 enters the tank adjacent its upper end and supplies the sewage, to be 55 treated, in a constant or intermittent flow as desired. A discharge pipe l3 located slightly below the level of the liquid, contained in the tank, permits the treated sewage tobe withdrawn from the tank. The liquid level in the tank may be maintained by regulating the water level in the chamber or tank into which the discharge pipe i3 empties.

An upright conduit II is located in the center of the tank, which is usually made circular, and the lower end of the conduit is supported in a predetermined spaced relation to the bottom of the tank to form a passage I5 through which the liquid, being treated, rises in the conduit l4. Desirably the area of the passage I5 approximately equals the cross-sectional area of the conduit ll. This arrangement causes a velocity of the moving liquid, in proximity to the passage l5, to be such that no settling will occur at the low point of the tank, to permit septicization of the sludge. The conduit I4 is preferably, although not necessarily, formed with a constricted throat l6 near its upper end, through which the velocity of the liquid is increased when the apparatus is in operation.

A bridge or truss structure ll extends across the top of the tank over the conduit, and supported by said bridge is a housing It in which is enclosed a motor l9 or equivalent'prime mover for rotating the aerator A. A conical bearing bracket '2!!- depends from the motor frame and containsanti-friction bearings for a shaft 2|, which connects the aerator with the motor.

The aerator forming the subject matter of this specification extends into the throat of the conduit I4, being axially disposed with respect thereto, and comprises a lower propelling element a, and an upper mixing member a The propelling element and mixing'member of the preferred form are shown as composed of one piece. The aerator is provided with a hub 23 by means of which it is mounted upon the shaft 2| and this also provides for vertical adjustment of the aerator with respect to the level of the liquid in the tank. The propelling element a preferably takes the form of'a. screw propeller or-conveyor, the blades 21 of which project from a cylindrical body portion 25 and are wound around said body portion from the lower end thereof along a sloping plane for some distance and then" are curved upward sharply as at 28 to the place indicated by the reference character 28 in Fig. 3. The marginoutward radially to their greatest radius which is at the place indicated by the reference character 28. Along the sharply curvedparts 28 of the blades 21, they extend substantially tangential with'respect to the body portion and at this place they act to impart a centrifugal action upon the liquid. Below the sharply curved part 28*, the blades 21 act to lift or propel the liquid upward at great velocity, the purpose of which will presently appear.

The mixing member a forms a continuation of the propelling element a in the preferred-embodiment of the invention and as shown, the mixing member comprises an inverted cone shaped body 24 which merges into the body portion 25 at its lower end, and mixing blades 26 that project from the cone shaped body and form continuations of the propeller blades 21. From the point 28, the blades 26 curve sharply forward in the direction of rotation of the aerator (see arrow x-in Fig. 3) and then slope upward and forward along the conical surface of the body 24, to the base thereof (see dotted lines 26 in Fig. 5) the free edges 29.0f the blades 26 being tipped downwardly as is clearly illustrated in Figs. 3 and 4 to form troughs between the conical face of the body 24 and the blades 26. It is also to be observed that the blades 26 diminish in width from the point 28 to the place where the blades terminate at the margin of the base of the cone shaped body 24, the marginal edges thereof being substantially. circular (in plan) from the point 28 to their extreme ends.' The lower end of the body portion of the aerator may be provided with a tapered tip 42 to provide a streamline flow and prevent eddies. The upper edge of the constricted part of the throat I6 of the conduit is desirably formed with an outwardly flaring portion 4| which gradually reduces the velocity of the liquid passing the aerator. y

In actual operation, the conveyor element a is more or less submerged in the liquid and the mixing member a is disposed above the level of the liquid in the tank.

The aerator is rotated at high speed and in operation the propeller blades 21 lift the liquid in the conduit and propel it upward against the cone shaped body 24 and blades 26. The liquid is propelled upward at a high velocity and is in a turbulent state during its upward travel. The velocity is such that as the liquid strikes the sharply curved parts 28 of the blades 26, it continues to move upward between the blades 26 and cone. Air is caught in the troughs between the blades 26 and cone and a partial vacuum is created behind said blades into which air rushes,

and since the upwardly moving liquid is in' a rolling and turbulent condition, the air is beaten into the liquid in abundant quantities and the liquid is thereby thoroughly aerated. Fromthe point 28 on the blades to their extremities at the base of the cone, a centrifugal action is imparted to the liquid and it is showered back upon the surface of the liquid in the tank. In some instances, a platform (not shown) is provided above the level of the liquid upon which the aerated liquid is thrown and from which it falls into the liquid in the tank. The liquid discharged from the conduit M by the aerator is replaced by liquid entering the conduit at its bottom and thus the liquid in the tank is circulated therein from top to bottom.

In the modified form, illustrated in Fig. 6, the two co-operating parts a, a of the aerator are separated, but are mounted upon the shaft 2|.

The cone 30 has the mixing blades 3| secured to or formed thereon and these blades have the entrapping edge portions 32 leading down along inclined planes to the more nearly upright sections 33 thereof. As in the preferred form the blades 3| are wrapped around the cone and incline forward in the direction of rotation toward the top of the cone. The propeller is spaced away from the mixing member and carries the propeller blades 35, which terminate in screw like sections 36 at their lower ends. The conduit l4, as in the preferred form, leads the liquid up from the bottom of the tank and the constricted throat l6 causes an increased velocity in proximity to the aerator.

The operation of this form of the invention is substantiallythe same as that of the preferred form. The propeller propels the liquid up against the mixer where air is beaten into the liquid as described in connection with the preferred form of the invention.

In the modified form illustrated in Fig. 7, the mixing member a is constructed substantially similar to the mixing member a shown in Fig. 6, and the propelling element a is spaced a considerable distance below the mixing member. Both mixing member and propelling element are mounted on the shaft 2| and rotate therewith. In this form of the invention, the propelling element is somewhat in the nature of a boat propeller having the usual hub 31 and blades 38 carried thereby. The blades are pitched to set up the desired velocity in the water in an upward direction.

In the modified form illustrated in Fig. 8, the

cone 39 and blades 460i the mixing member a are of substantially the same construction as that shown in Figs. 6 and 7 and the propelling element a is substantially of the same construction as the propeller illustrated in Fig. '7. The propeller is rigidly mounted on the shaft 2| and rotates therewith, but the mixing member may be rotatively mounted upon the shaft 2| as by bearings 43, or it may be stationarily mounted on the bracket 20 as desired. When rotatively mounted on the shaft, the liquid propelled against the blades 40 and cone 39 by the propeller, causes the mixing member to rotate in a reverse direction to that taken by the propeller, but nevertheless a very thorough aeration of the liquid is obtained. The same result is also obtained in cases where the mixing member is held stationary.

The aerator has been found to be particularly eflicient in the aeration of sewage, in sewage treatment plants which employ the activated sludge process. As is well understood, in this process, aerobic bacteria are employed, and abundant quantities of oxygen must be supplied to the bacteria. The aerator described, because of its peculiar characteristics, effectively beats air into the sewage in abundant quantities. It is equally adapted for impregnatingliquids with other gases in the treatment thereof.

I claim as new and desire to secure by Letters Patent:

1. An aerator, comprising a rotary liquid propelling element, and an opposed liquid deflecting cone having inclined blades thereon extending, in their entirety, along and outwardly from the conical face of the cone.

2. An aerator comprising a rotary liquid propelling element, an opposed conical deflecting member having blades thereon against which the liquid is propelled by the propelling element, and

means connecting said liquid propelling element and deflecting member to rotate in unison.

3. An aerator comprising a rotary screw propeller having inclined propelling blades-thereon, with their entering edges at 'the bottom of the blades and a conical body above said blades having inclined blades disposed along its conical face and '4. An aerator comprising a rotary liquid propelling element, a freely rotating conical memher having inclined blades thereon extending, in their entirety, along and outwardly from the conical face thereof. said conical member with its blades being disposed opposite to the propelling element and co-operating therewith to impregnate the propelled liquid with air, and separate bearings for the liquidpropelling element and conical member. l

5. An aerator comprising a rotary liquid propelling element, and a stationarily mounted conical mixing member having inclined blades thereon extending, in their entirety, along and outwardly from the conical face thereof, said mixing member being disposed opposite-to the propelling element and co-operating therewith to impregnate the propelled liquid with air.

6. An aerator comprising a rotary body formed with a cylindrical lower portion and an inverted cone like upper portion, propeller blades wound helically around the cylindrical portion of the .body, and mixing blades wound helically around the cone like portion in opposed relation to the propeller blades and merging into the same in sharply curved portions.

7. An aerator comprising an inverted cone shaped body terminating at its apex portion in a cylindrical portion, mixing blades wound around the conical portion of the body, and rev'ersely directed propelling blades wound around the cylindrical portion, the marginal edges of the mixing blades being approximately concentric with the axis of the cone, and the marginal edges or the propelling blades being spirally inclined toward the body portion.

8. An aerator comprising an inverted cone shaped body terminating at its apex portion in a cylindrical portion, downwardlytipped mixing blades wound around the conical portion of the body. and reversely directed propelling blades wound around the cylindrical portion, the marginal edges 01' the mixing blades being approximately concentric with the axis of the cone, and

. the marginal edges oi the propelling blades being ing into the mixing blades in sharply curved,

centrifugaily acting portions, the marginal edges oi the mixing blades being approximately concentric with the axis of the cone, and the marginal edges of the propelling blades being sprially inclined toward the body portion.

11. An aerator, comprising an upright shaft, a rotary liquid propeller mounted thereon, an opposed conical deflecting member disposed in coaxial alignment with said propeller and having curved blades thereon disposed in the path of liquid propelled by the propeller.

12. An aerator, comprising a rotary liquid propelling element, an opposed conical deflecting member, disposed in co-axial alignment with said propelling element and having blades thereon disposed in the path of liquid propelled by the propelling element, and means connecting said propelling element and deflecting means whereby they rotate together.

mans-rue 0. Donors. m. 

